The present invention relates to an embroidery data processing device for processing data to be used for forming an underlying stitch.
Conventionally, sewing data for sewing embroidery patterns is created by a skilled person such that a stitching point for each stitch cycle is determined. Recently, an embroidery data processing device which is capable of creating the sewing data automatically based on shapes, positions, sizes of embroidery patterns, direction of stitches, density of stitches and the like has been developed and widely used.
Among such data processing devices, there is a device for creating underlying stitch data which is used for performing an underlying stitch. The underlying stitch is carried out before an embroidery area is filled with embroidery stitches. By forming the underlying stitches beforehand, the embroidery stitches are formed thereupon, and the embroidery stitches can be seen to have an appropriate swell or three dimensional effect. In addition, the underlying stitches serve for preventing a work cloth from shrinking when the embroidery stitches are formed in succession on the underlying stitches. Examples of such a device are disclosed in Japanese Patent Provisional Publications HEI 2-307955, HEI 3-289989, and HEI 4-22393.
In the conventional data processing device described above, however, data processing for an area between an outline defining the outermost shape of an embroidery pattern, and outlines of areas included in the outermost outline (which will also be referred as an outer outline hereinafter) are not dealt with. Therefore, with the conventional embroidery data processing devices, it may not be possible to create appropriate sewing data for such areas under certain condition of the number, size, positions and the like of the outlines of the included areas (which will be referred to as inner outlines hereinafter).
For example, as shown in FIG. 6A, when underlying stitch data is to be created for a closed area A defined by the outermost outline OL and inner outlines IL1 and IL2 (i.e., the closed area which is inside the outermost outline OL, and outside of the inner outlines IL1 and IL2), the conventional data processing device has created the underlying stitch data as described below. Firstly, as shown in FIG. 6B, for each of inner outlines, a connecting lines is determined between another outline (for example, the outer outline). A reference point, which coincides with an end of the connecting line, is defined on each inner outline and, and a direction of the connecting line is determined to coincide with a direction similar to a predetermined direction of the underlying stitches. For example, if the direction of the underlying stitches is an up-down direction of FIG. 6B, the connecting line is determined from a lowest point of each inner outline and extends downward. Alternatively, the connecting line is determined to extend upwardly from a highest position of each inner outline. In FIG. 6B, shown is a case in which connecting lines CL1 and CL2 extend downwardly from the lowest points of the inner outlines IL1 and IL2, and respectively connect the inner outlines IL1 and IL2 with the outer outline OL.
Next, in order to prevent the underlying stitches from projecting out of the closed area A, an outline of a closed area B for the underlying stitches is determined such that the closed area (i.e., an underlying stitch area) B is apart from the closed area (i.e., an embroidery area) A by a distance "d" from the outer outline OL, inner outlines IL1 and IL2, and the connecting lines CL1 and CL2. The outline OL1 of the closed area B is shown by a broken line in FIG. 6B.
When the inner outlines IL1 and IL2 are arranged as shown in FIG. 7, and if the connecting lines CL1 and CL2 are determined as in the case shown in FIG. 6B, the outline OL1 would cross by itself as shown in FIG. 7 if the outline OL1 is defined as is done in the case shown in FIG. 6B. In such a case, it becomes impossible to identify the closed area in which the underlying stitch is to be carried out, and therefore, the underlying stitch data cannot be created.